Rotor blades for wind turbines are usually built as fibre-reinforced hollow composite structures. Hence, they are usually fabricated by impregnating respective aligned and orientated fibres or fibre clutches with a casting or resin material respectively. Respective connecting elements in the shape of studs or the like having respective connecting portions such as threaded holes are integrated within the casting material so as to provide an interface for a mechanical connection with respective corresponding connecting portions of a rotor hub such as threaded bolts or the like.
Thereby, removing of the cast rotor blade from the mould is oftentimes problematic since particularly in the region of the ring-like shaped root of the blade ovalisation may occur due to the self-weight of the rotor blade. Respective ovally shaped or deformed rotor blades are difficult to machine and particularly difficult to mount on a respective rotor hub of a wind turbine.
It has been proposed to strengthen the blade root by inserting respective metal rings in the region of the blade root while or before moulding. Another proposal to enhance the mechanical properties, in particular the stiffness of the blade root is to provide bulky circular plates with the blade root. This principle is of particular disadvantage regarding the manufacturing process of vacuum injection since the circular plates impair the insertion of a respective mandrel for injecting the casting material. Another proposal was to provide the blade root with additional material, i.e. increase wall thicknesses, etc. in the blade root.
The respective approaches for strengthening respective blade roots are deemed as comparatively cumbersome and costly.